The manufacture of many articles both large and small involves the use of metal plate components. One of the more efficient processes used in the fabrication of heavy metallic plate components is torch cutting. Multiple head torch cutting devices are now commonly used, and they permit the formation of a plurality of metal plate members both regular and irregular in configuration.
While torch cutting is one of the more efficient approaches to obtaining metal plate components of a desired shape, a problem results from the fact that, during the process, the plate momentarily reaches a melting temperature in the cutting area, producing slag along the edge of the component. The slag must be removed prior to use of the plate component in the fabrication process.
In addition to other grinding and surfacing functions, abrasive grinding machines have been found to be quite suitable for removing slag from such metal plate components. Slag grinding machines typically consist of an elongated, horizontal bed disposed approximately at the waist level of an operator and an endless belt that moves longitudinally over the bed for carrying the metal plate workpieces. An abrasive grinding head is carried by the machine frame in overlying relation to the bed and endless conveyor belt, itself consisting of a relatively wide endless abrasive belt that moves around a drive roller and one or more idler rollers. The grinding portion of the grinding head is disposed in spaced relation to the conveyor belt and elongated bed, and the abrasive belt normally moves in a direction opposite that of conveyor belt movement. Thus, as the workpieces are carried through the grinding area by the conveyor belt, they are engaged by the oppositely moving abrasive belt, which quickly removes the slag.
It is of course necessary for the elongated bed to provide a relatively rigid backing support to the workpiece in direct opposition to the grinding head in order for the workpiece to be forced into grinding engagement with the abrasive belt. Consequently, the elongated bed of a conventional slag grinding machine is continuously rigid over its length, or at the very least through the grinding area.
Slag grinding machines as described operate quite efficiently so long as the metal plate components are flat, since the planar backing surface of the elongated bed uniformly urges the plate component against the grinding head, uniformly removing the irregularly formed slag from all edge surfaces. A significant problem arises, however, if the plate components have become warped even to a minimal degree, which is quite common because of the heat involved in the torch cutting process. It will be readily appreciated that a warped metal plate passing through the grinding area over a fixed planar bed cannot be uniformly urged against the grinding head. If a slightly concave surface is subjected to the grinding head, the mid or low areas will not be completely ground, leaving an amount of slag. If the convex surface of the warped plate member is exposed to the grinding head, the mid-portion will be ground, but the ends or sides will be incompletely surfaced.
The problem is relatively acute even though the warpage is minimal, since a component having residual slag cannot be used in the fabrication unless this remaining slag is removed by hand.